Flexible sheet feeding mechanism



Feb. 11, 1969 COHN 3,427,018

FLEXIBLE SHEET FEEDING MECHANISM Filed Jan. 13, 1967 Sheet of 5 INVENTOR.

ROBERT COHN BY .AI TORNEYS Feb. 11, 1969 R. COHN FLEXIBLE SHEET FEEDING MECHANISM Filed Jan. 15, 1967 v INVENTOR. ROBERT ATTORNEYS Feb. 11, 1969 R. COHN FLEXIBLE SHEET FEEDING MECHANISM 3 of S Sheet Filed Jan. 15, 1967 INVENTOR.

United States Patent 7 Claims ABSTRACT OF THE DISCLOSURE This invention is a continuous sheet feeding mechanism which employs a pivotable suction gripping head to separate successively the bottom-most sheet of a stack of sheets and to assist in feeding the separated sheet over a curved feeding surface.

The invention relates generally to a feeding mechanism for flexible material in sheet form as in envelope machines, printing machines and the like. The mechanism includes a pivotable suction gripping head which deflects the lowermost sheet of the stack over a curved sheet feeding surface or roll and which pivots in relation to the curved feeding surface to maintain a sheet gripping surface of the head substantially in a plane tangential to the curved feeding surface at the line of contact between the sheet and the curved feeding surface. A pair of counterrotating stack support discs and a retractable finger separator normally support the stack and intermittently permit the suction gripping head successively to seize and, with feed segment means, to withdraw the lowermost sheet.

An important object of this invention is to provide a feeding mechanism in which successively the lowermost sheet of a stack of sheet material is deflected over a curved feeding surface by a suction gripping head without buckling of the sheet as it is deflected and then withdrawn from the bottom of the stack.

Another object of this invention is to provide a pivotable suction gripping head in which the angularity of its gripping surface is adjustable relative to the curved feeding surface, such as a roll having a fixed curvature, so that the gripping surface is maintained substantially in the plane tangential to the line of contact between the sheet being fed and the curved feeding surface.

One other object of this invention is to provide a pivotable suction gripping head which has several shaped suction orifices or a variety of contoured gripping surfaces which can be indexed from one orifice or surface to the other to more easily grip paper and other sheet material of various grades and thicknesses.

The foregoing objects and other advantages of the invention will become apparent from a consideration of the following description and the accompanying drawings in which:

FIG. 1 is a top plan view of the sheet feeding mechanism mounted on an envelope machine;

FIG. 2 is an enlarged elevational view of the suction gripping means in two positions taken along line 2-2 of FIG. 1;

FIG. 3 is a plan view of only the stack support discs and retractable finger separator shown in FIG. 1;

FIG. 4 is a perspective view showing one form of support and drive for the suction gripping head;

FIG. 5 is a sectional view also taken along the line 22 of FIG. 1 showing the relationship between the suction gripping means, the feed segment means and the feed roll;

FIG. 6 is a sectional view of the pivoted suction gripping head taken along line 66 of FIG. 5; and

FIG. 7 is a top plan view of only the suction gripping 3,427,018 Patented Feb. 11, 1969 ice means taken along line 77 of FIG. 5 with parts of the mechanism broken away for clarity of illustration.

A stack of sheet material 1 such as precut envelope blanks, for example, shown in hidden lines in FIG. 1 and in elevation in FIG. 2 rests upon a feed rack 2 oriented at an angle of about 60 with the horizontal. The upper margins of the stacked sheets extend beyond the feed rack and above a curved sheet feeding surface, which in the embodiment described, is a rotatable feed roll 3.

The suction gripping means deflects the lowermost sheet In of the stack over the curved sheet feeding surface or feed roll 3. The suction gripping means includes a pivotable suction gripping head 4 journaled upon a slotted hollow tube 5, shown in detail in FIG. 6, which communicates vacuum to the interior of the suction gripping head. The head itself has a gripping surface 6 pierced by suction gripping orifice 7 which communicates with the slot in slotted tube 5.

In the described embodiment articulated support tubes 8a, 8b depend from the drive shaft 9 which oscillates the slotted tube 5 and gripping head 4 in timed relation to the feed segment means 10 as will be hereinafter described. The support tubes 8a, 8b are made from tubular material and also conduct vacuum from a vacuum source as at 11 and interconnecting flexible conduit 12 to the slotted head support tube 5. Cam follower 13 fixed to the drive shaft 9 by crank 14 follows gripper cam 15 mounted on cam shaft 16. The gripper cam 15 oscillates drive shaft 9 through a small arc in the order of 30.

The suction gripping head carried from drive shaft 9 thus reciprocates between a sheet seizing position at the stack shown in solid lines in FIG. 2 to a release position shown in dotted lines at 4'. Valving means also operated from cam shaft 16 and referred to generally as 17 connects and disconnects the vacuum at source 11 from the suction gripping head. Vacuum communicates with the suction head continuously as it moves from its sheet seizing position to the release position. The vacuum disconnects at about the head position shown in hidden lines in FIG. 2 at 4'. At this point feed segment means 10 engages the single deflected sheet in between it and feed roll 3. The segment means in rolling contact with feed roll 3 Withdraws the deflected sheet from the stack and feeds it to subsequent processing stages of the machine. After release of the seized sheet, the suction gripping head travels beyond the position indicated at 4 to clear the deflected sheet 111 as it is withdrawn by the segment means.

Segment means 10 comprises a pair of spaced segments having at least one peripheral cutout 18 which accommodates intermittent deflection of the lowermost sheets. Segment drive shaft 19 rotates the segment means in timed relation to the oscillatory movement of the suction gripping head 4.

The suction gripping head 4 pivots on the slotted support tube 5 as can be most clearly seen in FIGS. 6 and 7. Head pulley 25, rotatable with head 4, carries a first timing belt 26. Travel of timing belt 26, of course rotates head pulley 25 and the suction gripping head 4 joined with it. In the articulated gripping mechanism described, timing belt 26 trains over double idler pulley 27 pivoted on a fixed stub shaft 28 mounted on the joint between the two portions 8a, 8b of the articulated support tube slightly eccentric with respect to the joint axis to maintain belt tension. The idler pulley 27 also carries a second timing belt 29 which in turn trains around adjustable timing pulley 30 secured to the machine frame 31. Timing pulley 30 is bolted to the frame 31 and does not rotate, but its axis is coincident with the axis of drive shaft 9.

The diameter of timing pulley 30 is larger than that of the idler pulley 2.7 and head pulley 25. Hence, as drive shaft 9 rotates the support tube assembly, lugged timing belt 29 rotates idler pulley 27, lugged timing belt 26 transmits this motion to head pulley 25 and suction gripping head 4. Therefore, selection of the ratio in diameters of timing pulley 30 and idler pulley 27 predetermines the amount of rotation of suction gripping head obtained between its sheet seizing position shown in solid lines in FIG. 2 and its release position shown in dashed lines in FIG. 2 at 4'. In this manner, the gripping surface of the head is maintained initially substantially parallel to the lowermost sheet in the stack, but pivots as it travels to the release position so that at 4' the gripping surface lies substantially in a plane tangential to the surface of feed roll 3 at its line of contact with the deflected lowermost sheet 1a. Thus it can be visualized in FIG. 2, the gripping surface of the head travels from the point of initial contact with the lowermost sheet to position 4 substantially in a series of planes tangent to the curved feed surface of roll 3 at the forwardmost lines of contact between the deflected sheet and the curved feed surface. As described, when the head reaches this position, the leading edge of drive segment means 10 engages the deflected sheet and by rolling contact against feed roll 3 moves it out from beneath the stack of sheet material and on to subsequent processing in the machine.

The support tubes 8a, 8b of the described embodiment are articulated to accommodate segment drive shaft 19. The joint is not necessary if one uses a split segment drive shaft. In that event, the head support tube may comprise a non-jointed tube pivoted from oscillatory drive shaft 9 at one end and carrying slotted head support tube at the other. Timing belt 29 in this construction trains directly over head pulley 25. Double idler pulley 27 and first timing belt 26 are then not necessary.

A retractable finger separator 35 and a pair of counterrotating stack support discs 36a, 36b combine to support the leading edge of the stack and prevent the balance of the stack from following the lowermost sheet as it is deflected away from the stack by suction gripping head 4. The separator comprises retractable finger 37 operated by separator cam follower 38 and separator cam 39 which also rotates on cam shaft 16. The finger retracts to permit gripping head 4 to deflect the lowermost sheet and then immediately moves back to help support the forward edge of the second lowermost sheet and the balance of the stack of sheets.

Stack support discs 36a, 36b counter-rotate in synchronism and in timed relation to the separator 35 and gripping head 4. The trailing edges 40a, 40b expose the cutout portions 41a, 41b of the discs just as the separator finger 37 retracts and the gripping head 4 seizes the lowermost sheet in the stack. The cutout portions 41a, 41b permit the gripping head to deflect the lowermost sheet and with the feed segment, to pull it from the stack through the plane of the discs before the leading edge 42a, 42b move into position with the separator finger to support the balance of the stack.

As an added feature, shown in FIG. 6, the suction gripping head may be provided with additional gripping orifices 7 of various shapes and gripping surfaces 6' in a variety of contours for different gripping services. Any particular surface and orifice combination can be used merely by rotating timing pulley 30 to index the gripping head 4 to the seizing position of the head 4 illustrated in FIG. 2 for that combination. Similarly, the angularity of the gripping surface in service is easily modified by a partial indexing of the gripping head by lesser rotation of the timing pulley 30.

I claim:

1. A mechanism for feeding the lowermost sheet of a stack of sheets comprising a frame, a curved feed surface fixed on said frame and spaced from said lowermost sheet over which said sheet is drawn; a suction gripping head for deflecting said lowermost sheet into contact with said curved feed surface; oscillatory support means carrying said gripping head from said frame for movement relative to said stack and said curved feed surface, said head having a gripping surface pivotable relative to said support means; means for pivoting said head and gripping surface to align said gripping surface substantially in a series of planes tangent to said curved feed surface at the lines of contact between said lowermost sheet and said curved feed surface; support means beneath said stack comprising a pair of counter-rotating support discs in intermittent contact with the forward margin of the lowermost sheet of said stack, said support discs having cutout portions which intermittently release support of the leading edge of the lowermost sheet of said stack in timed relation to oscillation of said oscillatory support means; and feed segment means in rolling contact with said curved feed surface for drawing the deflected lowermost sheet over said curved feed surface and through the plane of said discs at said cutout portions.

2. The mechanism of claim 1 wherein said curved feed surface is a cylindrical roll rotatable on said frame in intermittent rolling contact with said feed segment means.

3. The mechanism of claim 1 having the additional element of a retractable finger separator for the forward margin of said stack which retracts coincidently with the release of support by the cutout portions of said discs.

4. In a mechanism for feeding the lowermost sheet of a stack of sheets, the improvement comprising a curved feed surface spaced from said lowermost sheet over which said sheet is drawn; a suction gripping head for deflecting said lowermost sheet into surface contact with said curved feed surface; oscillatory support means carrying said gripping head for oscillatory movement about a first axis relative to said stack and said curved feed surface, said head having a gripping surface and being pivotable and independently indexable from said support means about a second aXis at the connection between said head and said support means; and means pivoting said head and gripping surface about said second axis to align, while maintaining a predetermined indexed position, said gripping surface substantially in a series of planes tangent to said curved feed surface at the forwardmost lines of contact between said lowermost sheet and said curved feed surface.

S. The improvement of claim 4 wherein said curved feed surface is a rotatable cylindrical roll.

6. The improvement of claim 4 wherein said oscillatory support means moves said head from a seizing position adjacent to the lowermost sheet of said stack near its forward margin to a release position remote from said stack and wherein said means pivoting said head simultaneously pivots said gripping surface from substantial parallelism with said lowermost sheet at said seizing position through a series of planes substantially tangential to said curved feed surface at the forwardmost lines of contact between said sheet and said curved feed surface.

7. The improvement of claim 4 wherein the means pivoting said head and gripping surface include a timing pulley on the axis of rotation of but not pivotable with said oscillatory support means; a head pulley aflixed to and pivotable with said gripping head, said head pulley and timing pulley being a fixed distance apart; and timing belt means trained over said timing and head pulleys.

EDWARD A. SROKA, Primary Examiner. 

